All In
by distantmuse
Summary: This is an AU of what could have happened between Mark and Addison in NYC if she'd kept the baby. Can Mark make Addison forget about Derek, and prove to her that he can be what she needs? Can they handle it when their baby has a birth defect? Maddison.
1. Chapter 1

_Gah, I don't know why I'm doing this! I swore I would quit writing fic since I don't really have time for it anymore, but I miss my Maddison, and this idea came into my head. I'm exploring an alternative to the way things could have been in NYC. Fasten your seatbelts. It's going to be an angsty ride._

* * *

The sound of a box of pills sliding back and forth in her Prada handbag taunted Addison as she carried it into the bathroom adjacent to Mark's bedroom, clad in a bathrobe and slippers that were far from her typical attire, and carrying a glass of water in her other hand. She unzipped the bag and examined the name on the box of pills: Mifepristone. Addison thought the pills would be the end of her problems, or at least one of them.

The first time Addison had thrown up, it had been from the smell of another woman's perfume on Mark's skin. She couldn't believe that he was stupid enough to come to bed without showering; she figured he must have wanted to get caught. The sugary, cotton candy top notes were far from elegant, and were definitely not close to any fragrance that Addison would wear; they were, however, exactly the kind of scent that the 23 year old nurse in pediatrics would wear. After she'd thrown up the next three mornings, she became suspicious enough to take a pregnancy test, and was shocked when the stick turned blue.

That was two weeks before. As Addison opened the box of abortion pills, she bitterly lamented the irony that Mark had gotten her pregnant so easily, the first time they were together. There had been plenty of opportunities in the past eleven years for Derek to get his wife pregnant – times when they had been too impassioned to bother with condoms, times that long surgeries had kept Addison from taking her birth control pills on time, or at all.

Addison took a deep breath and popped the three pills out of the blister pack and into her hand. She opened her mouth and placed the first on her tongue. It tasted horribly bitter on her sensitive taste buds. As she picked up the glass of water, images flashed through her mind. She saw the faces of patients she had delivered throughout her career, the devastated expressions of mothers who had lost their babies. How could she abort her own child when she'd seen the suffering of women who'd unwillingly lost theirs?

Addison spat the pill back out into her hand and curled her fingers around it. The sparkle of her wedding and engagement rings caught her eye and she sighed.

"I can't do this…" Addison muttered.

Before she could change her mind again, she quickly threw the three pills into the toilet and flushed it, watching the pills swirl down and away from her. She sank to the floor and squeezed her eyes shut, trying to will the tears away. No matter how much she had thought it might solve her problems, she knew it would only create a new one; a guilt that she would never be able to forget.

Addison allowed herself to calm down before she finally pulled herself back up off the floor. When she entered Mark's bedroom, she picked up a green sequined pillow from Mark's bed. It was one of her few additions to his décor since she had moved in, and it looked slightly out of place in his bachelor pad. She stuffed it into her robe and approached the mirror, examining herself in the mirror.

"I can't believe this…" Addison whispered, running her hand over her fake baby bump.

The sound of a throat clearing startled Addison a few moments later. She gasped when she saw Mark's reflection behind her in the mirror, and knew she had been caught, that he knew. She tried to gauge his reaction from his face, but it remained expressionless.

"Is it mine?" Mark finally asked after remaining silent for what seemed like an eternity to Addison.

Addison pulled the pillow from inside her robe and flung it on Mark's bed forcefully. "Of course it's yours. You're the only one I've been with in six months. _I'm_ not the cheater."

Mark sighed and peeled off his leather jacket, tossing it onto a nearby recliner. "What do you mean by that?"

"I'm not stupid, Mark." Addison spat. "I know about you and Charlene. And you and Erin. Do you want me to go on?"

Mark rubbed his face with his hand. "No."

"Why?" Addison demanded, forgetting about the baby for a moment and perching herself on the edge of Mark's bed. "Why would you do that to me?"

Mark slowly sunk down next to her and avoided her eyes by fidgeting with the hem of his shirt. "I wanted to hurt you."

Addison threw her hands up in frustration and tried to swallow the lump that was rising in her throat. "This from a man who claims to love me."

"I've heard you on the phone with Derek's voicemail." Mark murmured. "I heard you telling him how much you missed him, how much you loved him, how much you wish he'd come home. That hurt. I wanted to make a life with you, and you're stuck on him. Don't you remember the past three years? Don't you remember why you started crying on my shoulder every night? Why I used to hold you until you'd fall asleep? Everything else that led up to that night?"

"Of course I do." Addison mumbled.

"You're not mine, Addison." Mark said quietly. "You never have been. I'm beginning to wonder if you ever will be."

"That's ridiculous, Mark." Addison argued. "I moved in with you. I sleep next to you every night."

Mark reached into Addison's lap and held up her left hand, giving her a pointed look. "These say otherwise. These say that you still belong to my best friend, that you still love him. So do your unsigned divorce papers."

"You don't understand." Addison said, pulling her hand out of his grasp. "You've never been married. We shared 13 years of our life together. I can't get over him overnight, Mark. I… I love you both."

Mark turned so that he was looking directly into her eyes. "Are you ever going to love me the way you did him?"

"I hope so." Addison whispered. "I want to."

Mark was silent. Addison fiddled with her wedding rings and looked back at him. "You didn't seem surprised about the baby."

"I had my suspicions." Mark shrugged. "I heard you throw up a couple of mornings. Whenever we had sex, you'd complain if I touched your breasts."

"Why didn't you say anything, then?" Addison asked quietly.

"I figured if it was true, you'd tell me yourself… When you were ready."

"What are we going to do?" Addison wondered aloud.

"I'll probably be a terrible father." Mark said sadly. "I never had a good one of my own… But I'd like to try."

Addison took a deep breath and nodded. "So would I… But how can I trust you?"

"I'll never cheat on you again. No other women. I promise." Mark said.

"It's going to take me a while to trust you." Addison replied honestly.

"I know… But let me prove to you that I can be what you want." Mark said, taking Addison's hand in his. He scowled as the rings on her finger pressed into his skin. "You need to lose the rings. If we're going to do this, we both have to forget other people and focus on each other."

"You're right." Addison sighed. She twisted the rings off her finger with some effort, since they had practically become molded to her finger over the past eleven years, and dropped them into Mark's waiting hand.

Mark stared at the rings in his hand and fantasized about throwing them into the Hudson River, taking them to the OR with him and sawing them in half, or at the very least, throwing them down on the floor and stomping on them.

But he wasn't that dramatic. He silently stood and carried them across the room. Addison heard a drawer open behind her, and heard the clank as the rings hit its wooden bottom. She winced as she heard him slam the drawer shut.

"The divorce papers are in my office." Addison said quietly. "I'll get them tomorrow."

"Good." Mark's face softened, and he returned to his seat next to Addison, gently wrapping an arm around her shoulders.

"If you're just doing this because I'm pregnant, then I don't…" Addison began.

"I'm doing this because I love you, Addison." Mark assured her. "We deserve a shot at happiness."

"We can't be selfish anymore." Addison reminded him. "It's not just the two of us we have to think about. There's a baby now that we have to put before both of us."

"Shhh." Mark softly kissed Addison's forehead, and placed a gentle hand on her stomach. "I know. Don't worry, Addie. I'm all in."

* * *

_What do you think? Is it worth continuing?_


	2. Chapter 2

_So, I haven't written in a while, but I had a sudden flash of inspiration, and decided to give this another go._

* * *

Mark and Addison had decided to keep her pregnancy a secret to avoid powering the hospital rumor mill any more than they had for the past several weeks. However, word of their decision to have a relationship and be "exclusive" to each other had spread quickly.

Mark knew that's what he was about to hear about when his cotton-candy scented former bedmate bounced toward him in her too short white nurse's uniform one afternoon at work.

Charlene looked amused as she stopped in front of him. "So, I hear that you actually think you're going to have a relationship with Dr. Montgomery-Shepherd?"

She put extra emphasis on Derek's last name, which made Mark cringe. He slammed the chart he was reviewing closed and glared directly into her hazel eyes. "Yes. I know that I am, actually."

"She's never going to leave him for you," Charlene retorted. "You might as well save yourself the pain."

"Listen to me, and listen closely." Mark put his fist down on the counter. "You don't know a thing about my life or my relationship with Addison."

"I know enough about your relationship to know that she sent you running to my bed." Charlene said haughtily.

"I hate to break this to you, but you were just an easy lay." Mark said evenly. "I'm done with you. I'm ready for the real thing."

"Well…" Charlene gave her bleached-blonde locks a toss, "If you change your mind…"

Mark clicked his pen and shoved it back into his lab coat. "Don't worry. I won't."

Charlene snorted and shoved past him. Her eyes caught those of his girlfriend, who was approaching, and she gave her a little smirk. Addison took a deep breath and looked away and toward Mark, who was filing his chart.

"I thought we had talked about her." Addison commented, trying to keep her tone steady.

Mark sighed and rubbed his face. "I knew you would do this. If you had heard what I said to her, you wouldn't be preparing to lecture me right now."

"What did you say?" Addison asked, placing one hand on her hip.

"I told her I wasn't interested in her. I told her I wanted something real. That I wanted you." Mark said, looking directly into her eyes.

"Oh." Addison said softly.

"It's been less than a week since I told you that I am in this, and you already don't trust me." Mark said. Addison didn't miss the hurt note in his tone.

"I'm sorry." Addison murmured. "I'm just… Scared."

"I know you are." Mark took her hand. "I am too, believe me. What do we need to do?"

Addison leaned against the counter. "Well, I have an appointment with Emily next month." Addison named her favorite co-worker. "It's the 15th at 10 a.m."

"You couldn't get in sooner than that?" Mark's brow furrowed.

Addison sighed. "Well, I wanted to, but that was the soonest that we could find something that worked with all three of our schedules. I'm starting myself on pre-natal vitamins."

Mark looked amused. "Sure you don't want to be your own doctor?"

Addison rolled her eyes. "No. I don't think that would work well for the delivery. I want her because I want someone I can trust; someone who's not going to let this get all over the hospital. We're going to have to start clearing things off more."

"All right. I'll pencil you in." Mark gave her a wink, and she shoved him lightly.

"You'll be there?"

"I'll be there."

* * *

A few weeks later, Addison found herself feeling awkward lying on an exam table that she was usually standing beside, her feet up in the stirrups. She felt even more awkward because Mark was ten minutes late.

"Because you're almost 40, I think we should do an amniocentesis." Emily said, and was relieved when Addison nodded her agreement. "We'll schedule that for a few weeks from now. But for now, let's just take a look at what's going on here."

"All right." Addison agreed with a sigh. She hated to start without Mark, but she knew very well that Emily had appointments to keep.

Emily turned on the ultrasound machine. Addison pulled up her gown and allowed Emily to squeeze the cold, clear jelly onto her stomach as she shivered slightly. The other doctor was just about to touch the probe to her stomach when there was an insistent knock at the door.

"About time." Addison grumbled through gritted teeth as Mark walked briskly into the room.

"I'm sorry." Mark said breathlessly as he took a seat next to Addison and reached for her reluctant hand. "There were complications with my breast augmentation."

"Make them too big?" Addison retorted.

Mark rolled his eyes and squeezed her hand. "Give me a break, would you?"

Emily cleared her throat in an attempt to break the tension. "Well, Dr. Sloan, you are just in time for the show."

Mark focused his eyes on the screen, where Emily was creating a picture by running the probe over his girlfriend's slightly convex stomach. Mark squinted his eyes, trying to focus on the image and recall his OB/GYN rotation from many years before. His ears focused in on the sound from the machine, and his chiseled jaw dropped slightly at what he heard.

"Am I hearing… What I think I am hearing?" Mark asked slowly.

"Twins." Addison was shocked. She had intentionally not paid attention to the ultrasound that had been required before she had been given the abortion pills, and had never even suspected that she might be carrying twins, even though she thought she had gained a little more weight than would be typical for a single pregnancy. She had chalked it up to stress and overeating, not a second child.

"Yup…" Emily smiled. "You're about 13 weeks along. I know this is a lot to take in, so why don't I leave the picture up for you while I check on your bloodwork?"

Addison and Mark nodded silently, fixated on the picture on the scream. Addison waited until Emily was safely out of the room before breaking into an outburst.

"What are we going to do?!" Addison exclaimed. "TWO babies? How in the hell are we going to do this? I was concerned about us being responsible for two other lives, after what we have been through… But TWO?"

"Well…" Mark fumbled, in a state of shock himself. "We'll figure it out. It'll be fine."

"We can't raise two babies in your apartment!"

Mark took a deep breath, realizing that he was going to have to be the rational one for a change. "Well… There's the brownstone."

In the divorce papers, which Addison had yet to file much to Mark's frustration and annoyance, Derek had left the brownstone to her. Mark knew that living there wouldn't be an option. Addison hadn't returned there since Derek left. She had come to Mark with only the clothes on her back, and wouldn't even go back for her wardrobe or her favorite shoes. She'd gone for a whirlwind shopping spree on Fifth Avenue, replacing everything she owned.

Addison snorted. "Fat chance."

"Then why don't you file the papers?" Mark said for what seemed like the millionth time. He was trying hard not to pressure her, but it was becoming more and more difficult to lie beside his best friend's wife each night. "It'll be yours, we'll sell it, and we'll buy a place of our own?"

"I don't even want to walk in there to clean it out to sell!" Addison stated firmly.

Mark sighed. "Then we'll hire someone. We'll hire someone to clean it out, sell what they can, and donate the rest to charity."

"Okay…" Addison nodded. "Okay, that makes sense… You are remarkably calm about this."

"I'm… I'm still in shock, babe." Mark said, shaking his head at the screen. "A month ago, I had no plans to become a father, and now I'm going to have two children."

"I know what you mean." Addison whispered, looking at the screen. "It's… Kind of amazing though, isn't it? I mean, I look at these every day, but this one is mine, and I just… It doesn't seem real."

Mark brought her hand to his lips and gently kissed it. "I know…"

"Maybe this happened for a reason…" Addison said softly. "Maybe it was to bring us together, for good?"

Mark smiled. "I'd like to think so. We're going to be okay."

"I… I do love you." Addison said. "You know that, right?"

"Of course I do." He placed his lips gently against hers. "I love you, too."

Their moment was interrupted when Emily walked back into the exam room. She was trying to keep a neutral expression, but Addison could tell that something was bothering her. Her own face had looked like that plenty of times when she was about to be the bearer of bad news.

"Just tell me." Addison said softly.

Emily took a deep breath. "Okay… Well, I'm concerned because your AFP level is high…"

"What does that mean?" Mark directed his question at Addison rather than Emily.

He could see in Addison's eyes that something was seriously wrong. She chewed her lip. "It means… That one, or both, of our babies probably has a birth defect. Let me see the ultrasound."

Without waiting for a response from Emily, Addison sat up quickly and turned so that she was able to pull the computer to her. She murmured incoherent words to herself as her fingers flew over the equipment, trying to get a closer look. Mark sat there, dumbfounded, waiting for his girlfriend to fill him in more.

"This one is okay…" Addison finally determined, pointing to the baby on the left. "But this one…"

"What is it?" Mark asked, his voice becoming more urgent.

"It's spina bifida." Addison sighed.

* * *

_ Let me know if you think it is worth continuing!_


	3. Chapter 3

On the way home, Mark's brain was reeling with a thousand questions about their baby's condition, and Addison was doing her best to answer them. Though he was somewhat familiar with the birth defect, it was far from his area of expertise.

Mark couldn't stop thinking about how their life was never going to be the same. Instead of arguing about names or what color scheme to do the baby room in, they would have to discuss surgeries and treatments. Instead of teaching the child to walk, they knew they might have to face putting the child in a wheelchair.

But Addison hadn't stopped rambling the medical side of the equation.

"We'll have to consult with one of my colleagues to see what our best course of action is depending on how severe the condition is. Sometimes the fetus is operated on in-utero, and sometimes the fetus…"

"Addison, _stop_ calling our child a fetus!" Mark interrupted as he pushed open the door to his apartment. She had referred to the baby as a "fetus" since they left the hospital, and he found himself unable to take it anymore. "Stop talking about him like he is one of your nameless, faceless patients!"

"He or she _is _nameless and faceless!"

"No, he is not. He _will _have a name. He _will _have a face. It will be _our_ face. He's going to look like us." Mark took a deep breath. "He's going to be ours, and you have to stop talking about him in only a medical sense."

"I _have_ to call him a fetus, because the second I start talking about him like he is ours and not some baby I will only know surgically is the second I'm going to completely lose it!" Addison shot back. She sank down into Mark's couch and dropped her face into her hands.

"Hey." Mark's voice softened, and he took a seat beside her.

"We're being punished." Addison said through her tears. "We're being punished for having an affair."

Mark rubbed slow circles on her back. "Look, I don't spend much time talking to God, but he doesn't seem like the type of guy who would inflict pain on innocent babies to get back at their parents."

"Then why?" Addison looked up, and Mark wiped the tears from her cheeks with his fingertips. "Why is this happening to us?"

"Why does this happen to anyone?" Mark responded pointedly. "We're not exempt just because we're doctors. Instead of wondering why us, we need to focus on our baby's quality of life and making the best decisions for him."

Addison shook her head. "I don't get how you are so calm about this."

"I'm _not _calm." Mark answered. "I am absolutely terrified. I was already scared of being a terrible father, and now, we're having two babies, and one is going to have special needs. I have no idea _how_ we are going to handle this; I just know that we can, and we will. It's going to be incredibly difficult, but it's a manageable defect."

"You're right." Addison leaned her head on his shoulder and allowed him to stroke her hair. She took a few deep breaths to steady her breathing. "After all, we're surgeons… We know how to work under pressure."

Mark dropped a kiss on the top of her head. "Exactly."

Addison snuggled into his chest, grateful that Mark had his moments of logic and clarity. Mark ran his hand gently over her small baby "pooch" (and he only called it that in his head and never aloud to her). He wondered if they were having boys or girls, or one of each. He wondered if they would look like him, her, or both of them. Most of all, he wondered if could be a good father to them when he'd never had a real one of his own.

* * *

Mark has always said that as a plastic surgeon, he fixed what was on the outside to cure what was wrong on the inside. In truth, he didn't see how a set of D-cups could really cure anyone's insides. But, working with children was different.

Amy was a bubbly eight-year-old with one last surgery for her cleft lip and pallet to go. Mark's view on surgery had changed after he realized that he was going to be a father to a special needs child. In Amy's parents, he saw what was to come for him and Addison. The fear of surgery after surgery. The painful task of trusting your child to someone else's hands. He found himself with a better bedside manner than he'd had since medical school, before he had become jaded.

"One more surgery, and you'll have that superstar smile you've been telling me you've always wanted. Are you ready?" Mark asked as he and an orderly rolled Amy down the hall to the operating room.

Amy nodded slowly. "I'm a little scared, though… I know I've had surgery before, but, I get scared every time."

Mark patted the little girl's hand gently. "I know. But we talked about what's going to happen, remember? You know what to expect. It's going to hurt, but then you'll feel better, and then you'll be happy with your smile. You know I'll be with you every step of the way until you feel better."

"Right." Amy smiled. "Dr. Sloan, you're good with kids. You got any?"

Mark smiled slightly at the first time he has been able to answer that question without vigorous shaking of his head. "Yeah. I have twins on the way."

"Awesome!" Amy grinned. "You'll be a great dad. I know. I can tell."

It was at that moment that Mark and Amy passed Addison at the nurse's station in the hall. Unbeknownst to them, she had been watching their entire exchange with interest. Addison gently reached out to touch Mark's arm and whispered.

"I think so, too."

* * *

Back in her office, Addison stared at her divorce papers, neatly stacked against blue paper. After seeing Mark's calm, comforting demeanor in the hall with Amy, she'd known it was time to pull them out. He had told her that he was "all in," but she had to admit that she had yet to become "all in" herself. Signing the papers was the only way to get to that level.

There was just one blank line, waiting for her signature. She looked at the sonogram of the twins, propped up against her computer monitor. Without looking away from the grainy black and white picture, Addison snatched a pen off of her desk and signed "Addison Montgomery-Shepherd" on the line, knowing it was the last time that would ever been her name. As she sat back in her chair and stared at the signature, she realized she couldn't send the papers herself. Though she wanted to, she couldn't end the marriage herself that way.

She stood up from her desk and walked out to the reception area of her office. She held the papers out to her secretary, Jenna, along with a Post-It note with a phone number hastily scribbled on it in Addison's illegible doctor handwriting that only Jenna and pharmacists could decipher.

"Um… Could you…" Addison fumbled.

Jenna nodded silently. Besides being her secretary, Jenna had been a pretty good friend to Addison. She was one of the few people who knew the details of Mark and Addison's relationship, about the twins, and about the divorce. She took the papers from Addison's shaky grasp and crossed the room to the fax machine. Addison hung back and listened to the horrible noises that the machine makes as it dials Seattle. She watched as Jenna fed the machine each page that would end the last eleven years of her life.

As the fax machine beeped to signal that the transmission to Derek's lawyer was complete, Addison realized that she finally felt free to love Mark and their children.


End file.
